docs: def capitalize_argument(func):
      """
      Wraps a function that returns a string, adding the 'capitalize' argument.
  
      >>> capsified_fn = capitalize_argument(lambda *args, **kwargs: "what in the beeswax is this?")
      >>> capsified_fn()
      'what in the beeswax is this?'
      >>> capsified_fn(capitalize=True)
      'What In The Beeswax Is This?'
  
      """
      @six.wraps(func)
      def wrapped(*args, **kwargs):
          if "capitalize" in kwargs and kwargs['capitalize']:
              return func(*args, **kwargs).title()
          else:
              return func(*args, **kwargs)
      return wrapped